The Role of Surface Fluxes in MJO Propagation through the Maritime Continent

Abstract

The ‘barrier effect’ of the Maritime Continent (MC) is a known hurdle in understanding the propagation of the Madden-Julian Oscillation (MJO). To understand the differing dynamics of MJO events that propagate versus stall over the MC, a new tracking algorithm utilizing 30-96 day filtered NOAA Interpolated OLR anomalies is presented. Using this algorithm, MJO events can be identified, tracked, and described in terms of their propagation characteristics. Latent heat flux from OAFLUX, and CYGNSS surface winds and fluxes, are compared for MJO events that do and do not propagate through the MC. Events that successfully propagate through the MC demonstrate regional surface flux anomalies that are stronger, more-spatially coherent, and have a larger fetch. The spatial scale of convective anomalies for events that successfully propagate through the MC region is also larger than for terminating events. Large-scale enhancement of latent heat fluxes near and to the east of the Dateline, equally driven by dynamic and thermodynamic effects, also accompanies MJO events that successfully propagate through the MC. These findings are placed in the context of recent theoretical models of the MJO in which latent heat fluxes are important for propagation and destabilization.

A Cold Lid on a Warm Ocean: Indian Ocean Surface Rain Layers and Their Feedbacks to the Atmosphere

“…This effect initiates convection and facilitates column moistening that “preconditions” the free troposphere to deep convection prior to the active MJO (Ruppert Jr. & Johnson, 2016). Additionally, increased SSTs ahead of MJO convection may support propagation and maintenance of MJO convection by enhancing surface fluxes and frictional moisture convergence (Wang & Rui, 1990a; de Szoeke et al., 2015; DeMott et al., 2016; Zhang & Anderson, 2003; Hudson & Maloney, 2022). SST gradient‐induced moisture convergence may also play a role in recharging moist static energy prior to the active MJO (de Szoeke & Maloney, 2020).…”

imc-precip-iso: Open monthly stable isotope data of precipitation over the Indonesian Maritime Continent

“…On an intra-annual scale, precipitation over the IMC is also influenced by the Madden-Julian Oscillation (MJO), which propagates from the Indian Ocean to the Pacific Ocean via IMC (e. g. Ahn et al, 2020;Wei et al, 2020;Peatman et al, 2021;Bai and Schumacher, 2022;Abhik et al, 2023;Hudson and Maloney, 2023).…”